Figure 22a. Beam-hardening artifact in a 63-year-old man with respiratory failure. (a) On a CT scan, a pulmonary artery catheter causes adjacent beam-hardening artifacts within the main and right pulmonary arteries that mimic pulmonary embolism (arrows). Small pulmonary emboli are noted in the left pulmonary artery. (b) CT scan produced with bone window settings clearly depicts the pulmonary artery catheter. Adjacent beam-hardening artifacts are also seen.