To re-evaluate the appearance of the anterior diaphragm by the use of MDCT.

We performed a retrospective review of 81 consecutive patients that underwent chest CT by using 64 channel MDCT. We classified the anterior diaphragm as three types (types 1-3) based on 5 mm axial scans: a line behind the xiphoid, a discontinuity and opening anteriorly, and the presence of broad and poorly defined bands. We also classified the anterior diaphragm as three types (types A-C) using 2 mm sagittal reformation images, based on the shape of the anterior diaphragmatic fibers traveling from the base of the pericardium to the xiphoid: a downward slope, an upward slope, and a flat shape, and compared the two groups using a correlation determined by statistical analysis.

We could classify the appearance of the anterior diaphragm for all cases on the axial scans and sagittal reformation images. The number of types 1, 2, 3 on the axial scans was 30.9%, 38.3%, and 30.9% and the number of types A, B, C on the sagittal reformation images was 33.3%, 22.2%, and 44.4%, respectively. Type A was seen for 92% of type 1 cases, type C was seen for 88% of type 3 cases, and type B was seen for 54.8% of type 2 cases. The types seen between the axial and sagittal reformation images showed a significant agreement (r=0.868, p < 0.01).

The shape of the anterior diaphragm correlated with the relationship between the base of the pericardium and the xiphoid.