title: Model-based iterative reconstruction for reduction of radiation dose in abdominopelvic CT: comparison to adaptive statistical iterative reconstruction.
abstract: OBJECTIVE
  To evaluate dose reduction and image quality of abdominopelvic computed tomography (CT) reconstructed with model-based iterative reconstruction (MBIR) compared to adaptive statistical iterative reconstruction (ASIR).
  
  
  METHODS
  In this prospective study, 85 patients underwent referential-, low-, and ultralow-dose unenhanced abdominopelvic CT. Images were reconstructed with ASIR for low-dose (L-ASIR) and ultralow-dose CT (UL-ASIR), and with MBIR for ultralow-dose CT (UL-MBIR). Image noise was measured in the abdominal aorta and iliopsoas muscle. Subjective image analyses and a lesion detection study (adrenal nodules) were conducted by two blinded radiologists. A reference standard was established by a consensus panel of two different radiologists using referential-dose CT reconstructed with filtered back projection.
  
  
  RESULTS
  Compared to low-dose CT, there was a 63% decrease in dose-length product with ultralow-dose CT. UL-MBIR had significantly lower image noise than L-ASIR and UL-ASIR (all p<0.01). UL-MBIR was significantly better for subjective image noise and streak artifacts than L-ASIR and UL-ASIR (all p<0.01). There were no significant differences between UL-MBIR and L-ASIR in diagnostic acceptability (p>0.65), or diagnostic performance for adrenal nodules (p>0.87).
  
  
  CONCLUSIONS
  MBIR significantly improves image noise and streak artifacts compared to ASIR, and can achieve radiation dose reduction without severely compromising image quality.
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yasaka
authors.forename: Masaki
authors.initials: M
authors.lastname: Katsura
authors.forename: Masaaki
authors.initials: M
authors.lastname: Akahane
authors.forename: Jiro
authors.initials: J
authors.lastname: Sato
authors.forename: Izuru
authors.initials: I
authors.lastname: Matsuda
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
keywords: Adaptive statistical iterative reconstruction; Filtered back projection; Image noise; Model-based iterative reconstruction; Streak artifact