Normal Appendix in Adults: MDCT Findings about the Location, Thickness and the Presence or Absence of Intraluminal Gas

ABSTRACT

PURPOSE: We wanted to examine the usefulness of multi-detector CT (MDCT) with multiplanar reformations for evaluating the location, thickness and the presence or absence of intraluminal gas in the normal appendix of adults. MATERIALS AND METHODS: From December 2004 to June 2005, we evaluated normal appendices in 427 consecutive adult patients who were scanned with 16-slice MDCT. All these patients had no clinical findings of appendicitis. There were 251 men and 176 women. The age range was 19-84 years (mean age 55 years). The contrast-enhanced MDCT scans during the portal phase were obtained with 0.75 mm detector collimation and they were reviewed with using the multiplanar reconstruction images (3 mm section thickness). The MDCT images of normal appendices on a PACS monitor were retrospectively analyzed. We analyzed the location, thickness and the presence or absence of intraluminal gas by consensus of two abdominal radiologists. The positions of normal appendices were classified as type I (postileal and medial paracecal), type II (subcecal), type III (retrocecal and retrocolic or laterocolic), type IV (preileal and medial colic) and type V (lower pelvic cavity). RESULTS: The five types of appendiceal locations were as follows; type I (n=187; 44%), type II (n=78; 18 %), type III (n=92; 22%), type IV (n=39; 9%) and type V (n=31; 7%). The appendiceal tips in 29 cases (7%) were unusually located in the right subhepatic space, the small bowel mesentery and the right adnexa. The mean thickness of 427 appendices was 5.8+/-0.9 mm (range 3.8-9.2 mm). The appendiceal mean thickness was 5.9+/-0.9 mm in men and 5.7+/-0.9 mm in women (p < 0.05). 384 (90%) of 427 appendices had intraluminal gas and 43 (10%) had no intraluminal gas, and their mean thickness was 5.9 mm (range 3.8-9.2 mm) and 5.3 mm (3.8-7.3 mm), respectively (p < 0.05). CONCLUSION: MDCT with multiplanar reformations was useful for evaluating the location, thickness and the presence or absence of intraluminal gas in normal appendix of adults. These MDCT findings may be helpful in diagnosing equivocal appendicitis or appendicitis with unusual location.