AnatomyrnBecause of the transaxial plane of CT,the central portion of the diaphragm does not appear as a distinct structure,and its position can only be inferred by the position of the lung base above and the upper abdominal organs below.However,as the more peripheral portions of the diaphragm extend caudad toward their sternal and costal attachments,the anterior,posterior and lateral portions of the diaphragm become visible adjacent to retroperitoneal fat (Fig 1) /where the diaphragm is contiguous with the liver or spleen,it cannot usually be delineated by CT unless thin-collimation CT is used and a subdiaphragmatic fact layers is present.