title: The sternalis muscles: incidence and imaging findings on MDCT.
abstract: OBJECTIVE
  We studied the incidence and appearance of the sternalis muscles on multidetector computed tomography (MDCT) to permit the differentiation of the sternalis from significant pathologic condition.
  
  
  METHODS
  We retrospectively evaluated consecutive contrast-enhanced 16 row MDCT scans of the chest obtained in 1387 Korean patients (790 males and 597 females) between September 2003 and January 2005. All computed tomography scans were obtained in the supine position. Age ranges were 16 to 87 years and average was 59.2 years. Imaging analysis was based upon distribution (unilateral or bilateral, size, shape, and location). Statistical differences were evaluated by chi tests and Independent Samples t tests.
  
  
  RESULTS
  The sternalis muscle was present in 86 (6.2%) of 1387 patients. This muscle was more common in female (44 of 597, 7.3%) than in male (42 of 790, 5.3%) patients, but statistical significance was not noted (P=0.058). Twenty-three patients showed bilateral sternalis muscles. Among 63 patients with unilateral sternalis muscles, 28 patients showed left sternalis muscles and 35 patients showed right sternalis muscles. Unilateral distribution was more common. The height, AP diameter, and width of the sternalis muscle were not significantly different between unilateral and bilateral muscles (P=0.182, 0.911, and 0.114, respectively). The height and AP diameter showed no significant difference between male and female (P=0.470, 0.329, respectively) patients, but the width was wider in male (P<0.001) patients. All sternalis muscles showed flat appearance, except for 1 case. The sternalis muscles were located longitudinally in parasternal position in all cases.
  
  
  CONCLUSIONS
  The sternalis muscle is an unusual normal variant of the chest wall musculature running parallel to the sternum with various sizes and most sternalis muscles are flat on MDCT. Unilateral distribution is more common, and the size of muscle is larger in males. Its incidence is 6.2% in Korean population. Radiologists should be familiar with the image findings of the sternalis muscle to avoid any confusing pathologic lesions and facilitate its clinical use such as flap.
authors.affiliation: Department of Radiology, St Paul's Hospital, College of Medicine, The Catholic University of Korea, 620-56, Jeonnong-dong, Dongdaemun-gu, Seoul 130-709, South Korea.
authors.forename: Bae
authors.initials: B
authors.lastname: Young Lee
authors.forename: Jae
authors.initials: J
authors.lastname: Young Byun
authors.forename: Hak
authors.initials: H
authors.lastname: Hee Kim
authors.forename: Hyun
authors.initials: H
authors.lastname: Sook Kim
authors.forename: Song
authors.initials: S
authors.lastname: Mee Cho
authors.forename: Kang
authors.initials: K
authors.lastname: Hoon Lee
authors.forename: Kyung
authors.initials: K
authors.lastname: Sup Song
authors.forename: Bum
authors.initials: B
authors.lastname: Soo Kim
authors.forename: Jae
authors.initials: J
authors.lastname: Mun Lee
mesh_terms: D000328:Adult; D003287:Contrast Media; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D010369:Pectoralis Muscles / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D013249:Sternum; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media