Low-dose CT imaging of the acute abdomen using model-based iterative reconstruction: a prospective study
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.
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.
Low-dose abdominopelvic CT performed with MBIR is a feasible radiation dose reduction strategy for imaging patients presenting with acute abdominal pain.
KeywordsComputed tomography Iterative reconstruction Radiation dose reduction Acute abdominal imaging Dose optimization
Adaptive statistical iterative reconstruction
Automated tube current modulation
Body mass index
Filtered back projection
International Business Machines Corporation
Model-based iterative reconstruction
Sinogram affirmed iterative reconstruction
Size-specific dose estimate
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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