title: Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction.
abstract: OBJECTIVE
  To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging.
  
  
  METHODS
  A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDIvol) of each scan was taken from the dose report.
  
  
  RESULTS
  ASIR 40% significantly reduced CTDIvol (10.17±3.06mGy [FBP], 6.34±2.25mGy [ASIR] (p<0.001) by 37.6% and significantly increased CNRs (complete tumor-to-liver, 2.76±1.87 [FBP], 3.2±2.32 [ASIR]) (p<0.05) (complete tumor-to-muscle, 2.74±2.67 [FBP], 4.31±4.61 [ASIR]) (p<0.05) compared to FBP. Subjective scoring revealed no significant changes for diagnostic confidence (5.0±0 [FBP], 5.0±0 [ASIR]), visibility of suspicious lesion (4.8±0.5 [FBP], 4.8±0.5 [ASIR]) and artifacts (5.0±0 [FBP], 5.0±0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3±0.6 [FBP], 4.0±0.8 [ASIR]) (p<0.05), contrast (4.4±0.6 [FBP], 4.1±0.8 [ASIR]) (p<0.001) and visibility of small structures (4.5±0.7 [FBP], 4.3±0.8 [ASIR]) (p<0.001).
  
  
  CONCLUSIONS
  In clinical practice ASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure.
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: georg.boening@charite.de.
authors.forename: G
authors.initials: G
authors.lastname: Böning
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schäfer
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Grupp
authors.affiliation: Department of Radiation Oncology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Kaul
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kahn
authors.affiliation: Department of Gastroenterology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Pavel
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Maurer
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Denecke
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hamm
authors.affiliation: Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Streitparth
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CT; Dose reduction; Image quality; Iterative reconstruction; Neuroendocrine tumor