Course and variation of the intercostal artery by CT scan.
BACKGROUND
It is conventionally taught that the intercostal artery is shielded in the intercostal groove of the superior rib. The continuous course and variability of the intercostal artery, and factors that may influence them, have not been described in a large number of arteries in vivo.


METHODS
Maximal intensity projection reformats in the coronal plane were produced from CT scan pulmonary angiograms to identify the posterolateral course of the intercostal artery (seventh to 11th rib spaces). A novel semiautomated computer segmentation algorithm was used to measure distances between the lower border of the superior rib, the upper border of the inferior rib, and the position of the intercostal artery when exposed in the intercostal space. The position and variability of the artery were analyzed for association with clinical factors.


RESULTS
Two hundred ninety-eight arteries from 47 patients were analyzed. The mean lateral distance from the spine over which the artery was exposed within the intercostal space was 39 mm, with wide variability (SD, 10 mm; 10th-90th centile, 28-51 mm). At 3 cm lateral distance from the spine, 17% of arteries were shielded by the superior rib, compared with 97% at 6 cm. Exposed artery length was not associated with age, sex, rib space, or side. The variability of arterial position was significantly associated with age (coefficient, 0.91; P < .001) and rib space number (coefficient, - 2.60; P < .001).


CONCLUSIONS
The intercostal artery is exposed within the intercostal space in the first 6 cm lateral to the spine. The variability of its vertical position is greater in older patients and in more cephalad rib spaces.
Department of Radiology, University Hospitals Coventry and Warwickshire National Health Service (NHS) Trust, Coventry, England.
Emma J
EJ
Helm
Oxford Centre for Respiratory Medicine and Oxford Pleural Diseases Unit, Churchill Hospital, Oxford, England; National Institute of Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, England.
Najib M
NM
Rahman
Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada.
Omid
O
Talakoub
Department of Radiology, Taunton and Somerset NHS Foundation Trust, Taunton, England.
Danial L
DL
Fox
National Institute of Health Research (NIHR) Oxford Biomedical Research Centre, University of Oxford, Oxford, England; Department of Radiology, Oxford Radcliffe NHS Trust, Churchill Hospital, Oxford, England. Electronic address: Fergus.gleeson@nds.ox.ac.uk.
Fergus V
FV
Gleeson
D000368:Aged; D000792:Angiography / Q000379:methods; D001158:Arteries / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007366:Intercostal Muscles / Q000098:blood supply* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012272:Ribs / Q000098:blood supply; D014057:Tomography, X-Ray Computed