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European Radiology

, Volume 22, Issue 12, pp 2597–2606 | Cite as

Low-dose CT of the lung: potential value of iterative reconstructions

  • Stephan Baumueller
  • Anna Winklehner
  • Christoph Karlo
  • Robert Goetti
  • Thomas Flohr
  • Erich W. Russi
  • Thomas Frauenfelder
  • Hatem AlkadhiEmail author
Computed Tomography

Abstract

Objectives

To prospectively assess the impact of sinogram-affirmed iterative reconstruction (SAFIRE) on image quality of nonenhanced low-dose lung CT as compared to filtered back projection (FBP).

Methods

Nonenhanced low-dose chest CT (tube current-time product: 30 mAs) was performed on 30 patients at 100 kVp and on 30 patients at 80 kVp. Images were reconstructed with FBP and SAFIRE. Two blinded, independent readers measured image noise; two readers assessed image quality of normal anatomic lung structures on a five-point scale. Radiation dose parameters were recorded.

Results

Image noise in datasets reconstructed with FBP (57.4 ± 15.9) was significantly higher than with SAFIRE (31.7 ± 9.8, P < 0.001). Image quality was significantly superior with SAFIRE than with FBP (P < 0.01), without significant difference between FBP at 100 kVp and SAFIRE at 80 kVp (P = 0.68). Diagnostic image quality was present with FBP in 96% of images at 100 kVp and 88% at 80 kVp, and with SAFIRE in 100% at 100 kVp and 98% at 80 kVp. There were significantly more datasets with diagnostic image quality with SAFIRE than with FBP (P < 0.01). Mean CTDIvol and effective doses were 1.5 ± 0.7 mGy·cm and 0.7 ± 0.2 mSv at 100 kVp, and 1.4 ± 2.8 mGy·cm and 0.5 ± 0.2 mSv at 80 kVp (P < 0.001, both).

Conclusions

Use of SAFIRE in low-dose lung CT reduces noise, improves image quality, and renders more studies diagnostic as compared to FBP.

Key Points

Low-dose computed tomography is an important thoracic investigation tool.

Radiation dose can be less than 1 mSv with iterative reconstructions.

Iterative reconstructions render more low-dose lung CTs diagnostic compared to conventional reconstructions.

Keywords

Spiral computed tomography Image reconstruction Image enhancement Lung Radiation dosage 

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Copyright information

© European Society of Radiology 2012

Authors and Affiliations

  • Stephan Baumueller
    • 1
  • Anna Winklehner
    • 1
  • Christoph Karlo
    • 1
  • Robert Goetti
    • 1
  • Thomas Flohr
    • 2
  • Erich W. Russi
    • 3
  • Thomas Frauenfelder
    • 1
  • Hatem Alkadhi
    • 1
    Email author
  1. 1.Institute for Diagnostic and Interventional RadiologyUniversity Hospital ZurichZurichSwitzerland
  2. 2.Computed Tomography DivisionSiemens HealthcareForchheimGermany
  3. 3.Pulmonary Division, Department of Internal MedicineUniversity Hospital ZurichZurichSwitzerland

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