Ultra-low-dose CT combined with noise reduction techniques for quantification of emphysema in COPD patients: An intra-individual comparison study with standard-dose CT

H J Wisselink, G J Pelgrim, M Rook, K Imkamp, P M A van Ooijen, M van den Berge, G H de Bock, R Vliegenthart*

*Corresponding author for this work

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Abstract

Purpose: Phantom studies in CT emphysema quantification show that iterative reconstruction and deep learning based noise reduction (DLNR) allow lower radiation dose. We compared emphysema quantification on ultra-low dose CT (ULDCT) with and without noise reduction, to standard-dose CT (SDCT) in chronic obstructive pulmonary disease (COPD).

Method: Forty-nine COPD patients underwent ULDCT (third generation dual-source CT; 70ref-mAs, Sn-filter 100kVp; median CTDIvol 0.38 mGy) and SDCT (64-multidetector CT; 40mAs, 120kVp; CTDIvol 3.04 mGy). Scans were reconstructed with filtered backprojection (FBP) and soft kernel. For ULDCT, we also applied advanced modelled iterative reconstruction (ADMIRE), levels 1/3/5, and DLNR, levels 1/3/5/9. Emphysema was quantified as Low Attenuation Value percentage (LAV%,

Results: For ULDCT, the median radiation dose was 84 % lower than for SDCT. Median extent of emphysema was 18.6 % for ULD-FBP and 15.4 % for SDCT (inter-quartile range: 11.8-28.4 % and 9.2 %-28.7 %, p = 0.002). Compared to SDCT, the range in limits of agreement of emphysema quantification as measure of variability was 14.4 for ULD-FBP, 11.0-13.1 for ULD-ADMIRE levels and 10.1-13.9 for ULD-DLNR levels. Optimal settings were ADMIRE 3 and DLNR 3, reducing variability of emphysema quantification by 24 % and 27 %, at slight underestimation of emphysema extent (-1.5 % and-2.9 %, respectively).

Conclusions: Ultra-low-dose CT in COPD patients allows dose reduction by 84 %. State-of-the-art noise reduction methods in ULDCT resulted in slight underestimation of emphysema compared to SDCT. Noise reduction methods (especially ADMIRE 3 and DLNR 3) reduced variability of emphysema quantification in ULDCT by up to 27 % compared to FBP.

Original languageEnglish
Article number109646
Pages (from-to)1-8
Number of pages8
JournalEuropean Journal of Radiology
Volume138
DOIs
Publication statusPublished - May-2021

Keywords

  • Emphysema
  • Humans
  • Pulmonary Emphysema/diagnostic imaging
  • Radiation Dosage
  • Radiographic Image Interpretation, Computer-Assisted
  • Reference Standards

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