Gastrointestinal

European Radiology

, Volume 20, Issue 3, pp 630-639

Evaluation of image quality and lesion perception by human readers on 3D CT colonography: comparison of standard and low radiation dose

  • Valeria A. FisichellaAffiliated withDepartment of Radiology, Sahlgrenska University HospitalSahlgrenska Academy, University of Gothenburg Email author 
  • , Magnus BåthAffiliated withDepartment of Medical Physics and Biomedical Engineering, Sahlgrenska University HospitalDepartment of Radiation Physics, University of Gothenburg
  • , Åse Allansdotter JohnssonAffiliated withDepartment of Radiology, Sahlgrenska University HospitalSahlgrenska Academy, University of Gothenburg
  • , Fredrik JäderlingAffiliated withDepartment of Radiology, St. Göran’s Hospital
  • , Tommy BergstenAffiliated withDepartment of Radiology, Västra Frölunda Hospital
  • , Ulf PerssonAffiliated withDepartment of Radiology, Lindesberg Hospital
  • , Kristin MellingenAffiliated withDepartment of Radiology, Ullevål University Hospital
  • , Mikael HellströmAffiliated withDepartment of Radiology, Sahlgrenska University HospitalSahlgrenska Academy, University of Gothenburg

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Abstract

Aims

We compared the prevalence of noise-related artefacts and lesion perception on three-dimensional (3D) CT colonography (CTC) at standard and low radiation doses.

Methods

Forty-eight patients underwent CTC (64 × 0.625 mm collimation; tube rotation time 0.5 s; automatic tube current modulation: standard dose 40–160 mA, low dose 10–50 mA). Low- and standard-dose acquisitions were performed in the supine position, one after the other. The presence of artefacts (cobblestone and snow artefacts, irregularly delineated folds) and the presence of polyps were evaluated by five radiologists on 3D images at standard dose, the original low dose and a modified low dose, i.e. after manipulation of opacity on 3D.

Results

The mean effective dose was 3.9 ± 1.3 mSv at standard dose and 1.03 ± 0.4 mSv at low dose. The number of images showing cobblestone artefacts and irregularly delineated folds at original and modified low doses was significantly higher than at standard dose (P < 0.0001). Most of the artefacts on modified low-dose images were mild. No significant difference in sensitivity between the dose levels was found for polyps ≥6 mm.

Conclusions

Reduction of the effective dose to 1 mSv significantly affects image quality on 3D CTC, but the perception of ≥6 mm lesions is not significantly impaired.

Keywords

CT colonography Radiation exposure Image quality Threedimensional CT Colonic neoplasm