title: Blunt abdominal trauma: utility of 5-minute delayed CT with a reduced radiation dose.
abstract: OBJECTIVE
  To retrospectively evaluate the utility of 5-minute delayed computed tomography (CT) of the abdomen and pelvis by using a reduced radiation dose in patients with blunt abdominal trauma.
  
  
  METHODS
  Institutional review board consent was obtained, and written informed consent was waived. The study was HIPAA compliant. A total of 662 patients (497 men, 165 women; mean age, 40.5 years; range, 18-94 years) were identified who were evaluated with CT after blunt abdominal trauma during a 1-year period. Delayed CT scans were acquired 5 minutes after intravenous contrast material injection by using a decreased tube current of 100 mAs. Injury was identified in 106 patients. Two radiologists blinded to initial CT scan interpretation reviewed these cases to determine the quality and utility of delayed scans. Disagreement was settled by consensus. Delayed scans were considered useful when they aided in (a) characterizing initial CT findings, (b) identifying findings not present at initial CT, (c) excluding injury suggested at initial CT, and (d) increasing reader confidence with regard to initial CT findings.
  
  
  RESULTS
  All delayed scans were diagnostic. Delayed scans were useful in 27% (12 of 44) of patients with solid organ injury, 5.9% (one of 17) of patients with bowel or mesenteric injury, 4.5% (one of 22) of patients with pelvic fractures, and in none of the patients with free fluid only. Overall, delayed CT was useful in 2.1% (14 of 662) of all patients (95% confidence interval: 1.0, 3.2) referred for evaluation following blunt abdominal trauma. Utility increased to 13.2% (14 of 106) (95% confidence interval: 6.8, 19.7) in the group of patients with injury or suspected of having injury after initial CT.
  
  
  CONCLUSIONS
  If delayed CT scans are acquired when patients with blunt abdominal trauma are evaluated, selective, rather than routine, acquisition is recommended and a reduced radiation dose seems adequate.
authors.affiliation: Department of Radiology, Boston Medical Center, One Boston Medical Center Place, Boston, MA 02118, USA.
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Stuhlfaut
authors.forename: Brian C
authors.initials: BC
authors.lastname: Lucey
authors.forename: Jose C
authors.initials: JC
authors.lastname: Varghese
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Soto
mesh_terms: D000007:Abdominal Injuries / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*