Objective: To determine the wall thickness and external diameter values of the normal appendix on multidetector computed tomography (MDCT). Materials and methods. A senior radiologist with no knowledge of the patient's surgical history prospectively examined the abdominal-pelvic CT scans of 57 consecutive adult patients with no suspicion for appendicitis. Most of the patients (50/57) received an intravenous iodinated contrast material injection, but none had gastrointestinal studies. All slices (1 and 5 mm) and multiplanar reconstructions were analyzed on a treatment console. The external diameter of the appendix, the thickness of the two appendicular walls, and the presence or absence of intraluminal gas were noted.
Results: The appendix was visualized in 82% of the cases (47/57). The mean external diameter was 6.7 mm+/-1.2 (range, 5.0-11.0 mm). The mean thickness of the two walls was 4.8 mm+/-1.0 (range, 2.6-6.4 mm). Intraluminal air was visualized in 87% of cases (41/47).
Conclusion: Contrary to external diameter, the normal thickness of the appendix's two walls does not go beyond the threshold of 6 mm and therefore seems to be a reliable measurement for identifying a normal appendix using MDCT.