title: Counting ribs on CT by assessing costal attachments to the proximal xiphoid: is this method accurate?
abstract: OBJECTIVE
  To evaluate the usefulness of the method of counting ribs by assessing anatomic variations of the attachments of costal cartilages to the proximal xiphoid.
  
  
  METHODS
  From January to September 2005, 224 subjects (136 men, 88 women, age 13 to 89 years, mean age 55 years) underwent computed tomography examination of the chest. Axial images of the chest were obtained on a 16-slice multidetector computed tomography. Counting ribs was performed by using the medial clavicle as an anatomic landmark to identify the first costal cartilage. We analyzed variety and incidence of the attachment patterns of costal cartilages to the proximal xiphoid.
  
  
  RESULTS
  Out of the 224 patients, the last costal attachments to the proximal xiphoid were the sixth costal cartilages bilaterally for 2 (0.9%) subjects, one 6th and one 7th for 4 (1.8%) subjects, bilateral seventh for 191 (85.3%) subjects, one 7th and one 8th for 15 (6.7%) subjects, and bilateral eighth for 12 (5.4%) subjects.
  
  
  CONCLUSIONS
  The method of counting ribs from the proximal xiphoid is inaccurate because the sixth, seventh, and eighth costal cartilages may each attach to the proximal xiphoid.
authors.affiliation: Department of Diagnostic Radiology, Chung-Ang University College of Medicine, Seoul, South Korea.
authors.forename: Hwa Yeon
authors.initials: HY
authors.lastname: Lee
authors.forename: Seung Min
authors.initials: SM
authors.lastname: Yoo
authors.forename: In Sup
authors.initials: IS
authors.lastname: Song
authors.forename: Hyeon
authors.initials: H
authors.lastname: Yu
authors.forename: Jong Beum
authors.initials: JB
authors.lastname: Lee
authors.forename: Yang Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002356:Cartilage / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012272:Ribs / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014989:Xiphoid Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging*