Rib counting on CT using the sternal approach.

To devise a new method for counting ribs on CT scan, we evaluated the CT anatomy of the costal cartilages and the proximal xiphoid in 20 control patients without rib pathology. The sternal end of costal cartilages seen on the same image as the proximal xiphoid was always the seventh (n = 20). These costal cartilages were located anterolateral (n = 13) or lateral (n = 7) to the proximal xiphoid. In fifteen patients with rib pathology, 23 abnormal ribs were localized by our method. All of these ribs correlated with those seen on chest radiographs and rib cage views or with resected ribs on postoperative films.