Rib counting at CT with the clavicle as an anatomic landmark. Axial CT scan shows the medial third of the clavicle (*) and the relative position of the first two ribs (1, 2).
Identifying the first rib in relation to the clavicles is easy and precise; however, counting ribs from the clavicles is tedious for middle and lower rib lesions. Furthermore, counting thoracic vertebrae may be imprecise owing to partial volume effect.
Other methods: We can also use the xiphoid process, or the sternal angle as an anatomic landmark to determine the precise location of the ribs.