title: A prospective feasibility study of sub-millisievert abdominopelvic CT using iterative reconstruction in Crohn's disease.
abstract: OBJECTIVE
  Iterative reconstruction (IR) allows diagnostic CT imaging with less radiation exposure than filtered back projection (FBP). We studied an IR low-dose CT abdomen/pelvis (LDCTAP) protocol, designed to image at an effective dose (ED) approximating 1 mSv in patients with Crohn's disease (CD).
  
  
  METHODS
  Forty patients, mean age 37 ± 13.4 years (range 17-69), with CD underwent two synchronous CT protocols (conventional-dose (CDCTAP) and LDCTAP). CDCTAP and LDCTAP images were compared for diagnostic acceptability, yield, image quality and ED (in millisieverts). The optimal level of IR for LDCTAP was also studied.
  
  
  RESULTS
  LDCTAP yielded a mean ED of 1.3 ± 0.8 mSv compared with 4.7 ± 2.9 mSv for CDCTAP, reducing ED by 73.7 ± 3.3 % (mean dose reduction, 3.5 ± 2.1 mSv; P < 0.001) and dose length product by 73.6 ± 2.6 % (P < 0.001). Sub-millisievert (0.84 mSv) imaging was performed for patients with a body mass index (BMI) less than 25 (i.e. 63 % of our cohort). LDCTAP resulted in increased image noise and reduced diagnostic acceptability compared with CDCTAP despite use of IR, but detection of extra-luminal complications was comparable.
  
  
  CONCLUSIONS
  Patients with suspected active CD can be adequately imaged using LDCTAP, yielding comparable information regarding extent, activity and complications of CD compared with CDCTAP, but with 74 % less dose. LDCTAP at doses equivalent to that of two abdominal radiographs represents a feasible alternative to CDCTAP.
  
  
  CONCLUSIONS
  • Radiation dose is a concern when imaging patients with Crohn's disease. • New techniques allow low-dose abdominopelvic CT with acceptable image quality. • Using hybrid iterative reconstruction, its diagnostic yield compares well with that of conventional CT. • Sub-millisievert CT of patients with Crohn's disease appears technically and clinically feasible.
authors.affiliation: Department of Radiology, Cork University Hospital, Wilton, Cork, Ireland.
authors.forename: Siobhan B
authors.initials: SB
authors.lastname: O'Neill
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Mc Laughlin
authors.forename: Lee
authors.initials: L
authors.lastname: Crush
authors.forename: Owen J
authors.initials: OJ
authors.lastname: O'Connor
authors.forename: Sebastian R
authors.initials: SR
authors.lastname: Mc Williams
authors.forename: Orla
authors.initials: O
authors.lastname: Craig
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Mc Garrigle
authors.forename: Fiona
authors.initials: F
authors.lastname: O'Neill
authors.forename: Jackie
authors.initials: J
authors.lastname: Bye
authors.forename: Max F
authors.initials: MF
authors.lastname: Ryan
authors.forename: Fergus
authors.initials: F
authors.lastname: Shanahan
authors.forename: Michael M
authors.initials: MM
authors.lastname: Maher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000737:chemistry; D003424:Crohn Disease / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media