title: CT following US for possible appendicitis: anatomic coverage.
abstract: OBJECTIVE
  To determine superior-inferior anatomic borders for CT following inconclusive/nondiagnostic US for possible appendicitis.
  
  
  METHODS
  Ninety-nine patients with possible appendicitis and inconclusive/nondiagnostic US followed by CT were included in this retrospective study. Two radiologists reviewed CT images and determined superior-inferior anatomic borders required to diagnose or exclude appendicitis and diagnose alternative causes. This "targeted" coverage was used to estimate potential reduction in anatomic coverage compared to standard abdominal/pelvic CT.
  
  
  RESULTS
  The study group included 83 women and 16 men; mean age 32 (median, 29; range 18-73) years. Final diagnoses were: nonspecific abdominal pain 50/99 (51%), appendicitis 26/99 (26%), gynaecological 12/99 (12%), gastrointestinal 9/99 (10%), and musculoskeletal 2/99 (2%). Median dose-length product for standard CT was 890.0 (range, 306.3 - 2493.9) mGy.cm. To confidently diagnose/exclude appendicitis or identify alternative diagnoses, maximum superior-inferior anatomic CT coverage was the superior border of L2-superior border of pubic symphysis, for both reviewers. Targeted CT would reduce anatomic coverage by 30-55% (mean 39%, median 40%) compared to standard CT.
  
  
  CONCLUSIONS
  When CT is performed for appendicitis following inconclusive/nondiagnostic US, targeted CT from the superior border of L2-superior border of pubic symphysis can be used resulting in significant reduction in exposure to ionizing radiation compared to standard CT.
  
  
  CONCLUSIONS
  • When CT is used following inconclusive/ nondiagnostic ultrasound, anatomic coverage can be reduced. • CT from L2 to pubic symphysis can be used to diagnose/exclude appendicitis. • Reduced anatomic coverage for CT results in reduced exposure to ionizing radiation.
authors.affiliation: Joint Department of Medical Imaging, University of Toronto, Princess Margaret Hospital, 3-920, 610 University Avenue, Toronto, Ontario, M5G 2 M9, Canada. martin.o'malley@uhn.ca.
authors.forename: Martin E
authors.initials: ME
authors.lastname: O'Malley
authors.affiliation: Joint Department of Medical Imaging, University of Toronto, Toronto General Hospital, NCSB 1C572, 585 University Avenue, Toronto, Ontario, M5G 2 N2, Canada. drfawazalharbi@gmail.com.|Department of Medical Imaging, Qassim University, Buraydah, Qassim, Saudi Arabia. drfawazalharbi@gmail.com.
authors.forename: Fawaz
authors.initials: F
authors.lastname: Alharbi
authors.affiliation: Joint Department of Medical Imaging, University of Toronto, Mount Sinai Hospital, Room 567, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada. tchawla@mtsinai.on.ca.
authors.forename: Tanya P
authors.initials: TP
authors.lastname: Chawla
authors.affiliation: Joint Department of Medical Imaging, University of Toronto, OPG Building, 2nd Floor, North Side, 700 University Avenue, Toronto, Ontario, M5G 1X6, Canada. hadas.moshonov@uhn.ca.
authors.forename: Hadas
authors.initials: H
authors.lastname: Moshonov
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D000368:Aged; D001064:Appendicitis / Q000000981:diagnostic imaging*; D001065:Appendix / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010388:Pelvis / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011860:Radiography, Abdominal; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography; D055815:Young Adult
keywords: Anatomy; Appendicitis; Multidetector computed tomography; Radiation; Ultrasound