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Emergency Radiology

, Volume 26, Issue 2, pp 169–177 | Cite as

Low-dose CT imaging of the acute abdomen using model-based iterative reconstruction: a prospective study

  • Fiachra Moloney
  • Karl James
  • Maria Twomey
  • David Ryan
  • Tyler M. Grey
  • Amber Downes
  • Richard G. Kavanagh
  • Niamh Moore
  • Mary Jane Murphy
  • Jackie Bye
  • Brian W. CareyEmail author
  • Sean E. McSweeney
  • Conor Deasy
  • Emmett Andrews
  • Fergus Shanahan
  • Michael M. Maher
  • Owen J. O’Connor
Original Article

Abstract

Objectives

Performance of a modified abdominopelvic CT protocol reconstructed using full iterative reconstruction (IR) was assessed for imaging patients presenting with acute abdominal symptoms.

Materials and methods

Fifty-seven patients (17 male, 40 female; mean age of 56.5 ± 8 years) were prospectively studied. Low-dose (LD) and conventional-dose (CD) CTs were contemporaneously acquired between November 2015 and March 2016. The LD and CD protocols imparted radiation exposures approximating 10–20% and 80–90% those of routine abdominopelvic CT, respectively. The LD images were reconstructed with model-based iterative reconstruction (MBIR), and CD images with hybrid IR (40% adaptive statistical iterative reconstruction (ASIR)). Image quality was assessed quantitatively and qualitatively. Independent clinical interpretations were performed with a 6-week delay between reviews.

Results

A 74.7% mean radiation dose reduction was achieved: LD effective dose (ED) 2.38 ± 1.78 mSv (size-specific dose estimate (SSDE) 3.77 ± 1.97 mGy); CD ED 7.04 ± 4.89 mSv (SSDE 10.74 ± 5.5 mGy). LD-MBIR images had significantly lower objective and subjective image noise compared with CD-ASIR (p < 0.0001). Noise reduction for LD-MBIR studies was greater for patients with BMI < 25 kg/m2 than those with BMI ≥ 25 kg/m2 (5.36 ± 3.2 Hounsfield units (HU) vs. 4.05 ± 3.1 HU, p < 0.0001). CD-ASIR studies had significantly better contrast resolution, and diagnostic acceptability (p < 0.0001 for all). LD-MBIR studies had significantly lower streak artifact (p < 0.0001). There was no difference in sensitivity for primary findings between the low-dose and conventional protocols with the exception of one case of enteritis.

Conclusions

Low-dose abdominopelvic CT performed with MBIR is a feasible radiation dose reduction strategy for imaging patients presenting with acute abdominal pain.

Keywords

Computed tomography Iterative reconstruction Radiation dose reduction Acute abdominal imaging Dose optimization 

Abbreviations

ASIR

Adaptive statistical iterative reconstruction

ATCM

Automated tube current modulation

BMI

Body mass index

CD

Conventional dose

DLP

Dose-length product

FBP

Filtered back projection

GE

General Electric

IBM

International Business Machines Corporation

IR

Iterative reconstruction

LD

Low dose

MBIR

Model-based iterative reconstruction

SAFIRE

Sinogram affirmed iterative reconstruction

SSDE

Size-specific dose estimate

ED

Effective dose

SNR

Signal-to-noise ratio

Notes

Compliance with ethical standards

Ethical approval was granted and informed consent obtained from patients presenting with acute abdominal symptoms to the emergency department in a tertiary referral hospital between November 2015 and March 2016.

Conflict of interest

Ms. Jackie Bye is an employee of General Electric Healthcare and provided CT applications support for this project. The other authors declare that there is no conflict of interest regarding the publication of this paper.

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Copyright information

© American Society of Emergency Radiology 2018

Authors and Affiliations

  • Fiachra Moloney
    • 1
  • Karl James
    • 1
  • Maria Twomey
    • 1
  • David Ryan
    • 1
  • Tyler M. Grey
    • 2
  • Amber Downes
    • 2
  • Richard G. Kavanagh
    • 1
  • Niamh Moore
    • 1
  • Mary Jane Murphy
    • 1
  • Jackie Bye
    • 3
  • Brian W. Carey
    • 1
    Email author
  • Sean E. McSweeney
    • 1
  • Conor Deasy
    • 4
  • Emmett Andrews
    • 5
  • Fergus Shanahan
    • 6
    • 7
  • Michael M. Maher
    • 1
    • 7
  • Owen J. O’Connor
    • 1
    • 7
  1. 1.Department of Radiology, Cork University HospitalUniversity College CorkCorkIreland
  2. 2.School of MedicineUniversity College CorkCorkIreland
  3. 3.GE HealthcareChicagoUSA
  4. 4.Department of Emergency MedicineCork University HospitalCorkIreland
  5. 5.Department of Surgery, Cork University HospitalUniversity College CorkCorkIreland
  6. 6.Department of Medicine, Cork University HospitalUniversity College CorkCorkIreland
  7. 7.Alimentary Pharmabiotic CenterCorkIreland

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