The mean transverse diameter of the normal appendix is as high as 7 to 8 mm on noncontrast CT. The individual wall of the appendix is usually pencil thin, In a series of rectal contrast CT cases, gas was present in the lumen in 57% of normal appendices, versus 19% in infiamed appendices.he appendix, which contains gas, is seen (A) abutting the medial edge of the right hepatic lobe in one patient (arrow), and (B) anterior to the liver in another patient (arrow). When determining if appendicitis is present, all of the CT findings should be integrated in making this determination.