CT OF SABER-SHEATH TRACHEA - CORRELATION WITH CLINICAL, CHEST RADIOGRAPHIC AND FUNCTIONAL FINDINGS

The diagnosis of saber-sheath trachea is easy at CT due to its cross-s ectional imaging, but the significance of this CT sign has not been ev aluated in the diagnosis of chronic obstructive pulmonary disease (COP D). Various signs of COPD were compared between a series of 20 patient s with a saber-sheath trachea at CT (tracheal index less than or equal to 66%) and a group of 20 pneumologic control patients without saber- sheath trachea (tracheal index greater than or equal to 70%). These si gns included clinical and standard radiographic indices of COPD, stern um-spine distance and 3 functional tests of COPD: forced expiratory vo lume in one second, carbon monoxide diffusing lung capacity, and funct ional residual capacity (FRC). A significant difference was found betw een the 2 groups, concerning the values of FRC (p<10(-4)) and of stern um-spine distance (p<10(-2)). The tracheal index was significantly cor related with the FRC values (r=-0.611; p<10(-5)) and with the sternum- spine distance (r=-0.322; p<0.05). No other significant difference was observed. It is concluded that saber-sheath trachea is basically a si gn of hyperinflation.